In general, skin oil such as sebum is present on the skin surface besides moisture, and forms a sebum coating in the state of emulsion to cover and protect the skin or hair. The chemical composition of sebum forming such a sebum coating is very complex and includes free fatty acids, higher alcohols, higher hydrocarbons or other components forming oily substances, besides various oily substances. Thus, it is preferred that materials of a cosmetic agent are close to the oily substances present physiologically on the skin surface.
Therefore, oily materials are important ingredients of a cosmetic agent in addition to aqueous materials. Such oily materials may be classified into fat and oil, wax, higher hydrocarbons and synthetic esters disclosed herein, depending on the chemical structure or property thereof.
The synthetic ester oil used as a raw material of a cosmetic agent is provided for the purpose of manifesting the advantages of natural esters such as fat and oil and wax and improving the disadvantages thereof. Use of such synthetic ester oil is increasingly in demand as a substitute for the conventional silicone.
According to the related art, there has been generally used a cosmetic agent which contains liquid oil, such as paraffin, esters, higher alcohols or glycerides, to provide softness, smoothness, emollient effect, or the like. However, such a cosmetic agent is disadvantageous in that it causes an oily and sticky feel and oil coating-like appearance. Thus, in order to reduce an oily and sticky feel and oil coating-like appearance, silicone oil such as dimethylpolysiloxane is incorporated to the cosmetic agent in the art. Korean Patent Laid-Open No. 2005-0069835 discloses a hydrated type cosmetic composition using a silicone base, which utilizes a silicone crosslinked polymer to incorporate a larger amount of aqueous phase, has no preservative, and can be stored for a long time.
However, while silicone oil is spread lightly and has excellent smoothness and water repellency, it has poor compatibility with hydrocarbon-based liquid oil. In addition, since silicone oil has low surface tension, it diffuses rapidly and thus shows low durability.